The field of the invention is vaccine and diagnostic biomarkers. More particularly, the invention relates to a set of biomolecules as diagnostic biomarkers for distinguishing between vaccinated and infected animals and between M. ap. and M. bovis. 
Mycobacterial infections cause significant health problems to humans and animals including human tuberculosis, bovine tuberculosis, and Johne's disease. Johne's disease (aka paratuberculosis) is caused by infection with Mycobacterium avium subspecies paratuberculosis (M. ap); this disease causes severe economic losses estimated at $500 million per year for the US dairy industry alone, and these infections constitute a problem for 91% of dairy herds. Bovine tuberculosis, which is caused by infection with M. bovis, is endemic in dairy herds in several parts of the developing world and a significant problem for the wildlife animals in several developed countries (e.g., UK, USA, and Australia).
Current diagnostics can detect mycobacterial infections in cattle that have started to shed the bacteria or developed an antibody response. The available diagnostic tools are unreliable to detect early stages of infection or to differentiate infected from vaccinated animals (aka the DIVA principle). Early detection of mycobacterial infections is imperative to control the infection in herds. Further, the availability of a DIVA-based assay will facilitate adoption of new vaccines that can prevent M. ap infection.
Needed in the art are methods or diagnostic tools for detecting early stages of mycobacterial infection. Additionally, needed in the art are methods or diagnostic tools for distinguishing vaccinated from infected animals and distinguishing M. ap. from M. bovis pathogens in infected animals.